Axial turbine combined with reverse turbine

ABSTRACT

A main axial turbine combined with a reverse turbine, the rotors of both turbines being mounted on the same common rotor shaft, with the reverse turbine housing suspended coaxially within the outlet portion of the main axial turbine by a symmetrical system of support plates or vanes, is disclosed.

Lohonen et a1.

1451 Aug. 27, 1974- AXIAL TURBINE COMBINED WITH REVERSE TURBINE Inventors: Paavo Lohonen; 010i Karlsson, both of Finspong, Sweden Assignee: Stal Laval Turbin AB, Finspong,

Sweden Filed: Oct. 15, 1973 Appl. No.: 406,557

Foreign Application Priority Data Oct. 20, 1972 Sweden 13563/72 u.s. c1. .Q 415/153, 415/219 R 1m. (:1. F0ld 1/30, F0111 1/04 Field of Search 415/153, 152, 194, 198, 415/219 R [56] References Cited UNITED STATES PATENTS 725,184 4/1903 Webster 415/153 1,243,131 10/1917 Belluzzo 415/153 1,315,153

9/1919 Peterson 415/153 Primary ExaminerHenry F. Raduazo 711 ABSTRACT A main axial turbine combined with a reverse turbine, the rotors-of both turbines being mounted on the same common rotor shaft, with the reverse turbine housing suspended coaxially within the outlet portion of the main axial turbine by a symmetrical system of support plates or vanes, is disclosed.

5 Claims, 5 Drawing Figures PATENTEnauszvxsm SHEET 1 BF 2 Fig. I

PAIE-NTEMuszmn SHEET 2 BF 2 ill AXIAL TURBINE COMBINED WITH REVERSE TURBINE BACKGROUND OF THE INVENTION For many installations, it is necessary to provide both forward and reverse turbines. In marine turbines, for example, the main turbine for forward propulsion must be accompanied by a reverse turbine to enable the ship to back, since it is normally not possible to reverse a single turbine. In such cases, the reverse turbine is usually located on an extension of the main turbine shaft at the outlet end of the main turbine. If the ship is provided with both high and low pressure turbines, the reverse turbine is normally positioned on the low pressure turbine so that it is in direct communication with the condenser.

Prior art arrangements for combined forward and reverse turbines, have the reverse turbine housing suspended from an open inspection shaft arranged diametrically in the outlet portion of the main turbine housing. This requires that the inpsection shaft be constructed of sufficient strength and size to bear the load, which results in a rather large and bulky installation.

SUMMARY OF THE INVENTION The present invention provides an arrangement for suspension of the reverse turbine housing within the outlet portion of the main turbine housing in combined turbine installations, in a manner which avoids the de' velopment of potentially damaging asymmetry and outof-true distortion from thermally induced movements in the turbine structure.

Specifically, according to the invention, a symmetrical system of supporting plates or vanes is mounted within, and secured to, the outlet portion of the main turbine housing. In turn, the reverse turbine housing, or its outlet end portion, is attached to and suspended within the symmetrical plate system. A framework of connecting struts joins the reverse turbine stator housing and its outlet end portion symmetrically and circumferentially around their outer periphery.

This arrangement provides symmetrical suspension of the reverse turbine, unaffected by thermal variations in the turbines, and, by structurally unloading the open inspection shaft of the main turbine, permits lighter construction and more freedom in the placement of this shaft, thereby making possible a shorter more compact turbine unit.

These and other features of this invention will be fully described with reference to the accompanying drawings, and the concepts herein disclosed will be defined by the appended claims.

DRAWINGS FIG. 4 is a longitudinal sectional view of a modified embodiment of this invention; and

FIG. 5 is a cross-sectional view of the embodiment of FIG. 4.

DESCRIPTION I portion 1 of the main turbine and which maintain housing 2 in coaxial relationship to outlet portion 1. With this arrangement, clearly seen in FIGS. 2 & 3, temperature differences between reverse turbine housing 2 and outlet portion lwill cause plates 3 to bend without disturbing their centering effect, by virtue of the systems symmetry.

On reverse turbine housing 2, a framework of struts or stays 4, arranged circumfe'rentially, is connected symmetrically and supportively to outlet end portion 5. End portion 5 is provided with an opening and a seal for turbine shaft 21 and carries shaft bearing 6. Supporting struts 4 may bend with temperature fluctuations between reverse turbine housing 2 and outlet end piece 5, but their centering effect will be maintained by their symmetrical configuration.

Steam inlet 7 to reverse turbine 2 is carried by outlet portion 1 of the main turbine and is provided with telescopic piston ring seal 8; similarly, pressure equalizing tube 9, carried on the opposite side of outlet portion 1 to reduce the bending force on support plates 3, is also provided with a telescopic piston ring seal 8.

Bearing 6 for rotor shaft .21 may be reached, even while the turbine is in operation, through inspection chamber 14 on an open shaft 10, which is sealed against end portion 5 carrying bearing 6. This construction, leaving shaft 10 unloaded, nonforce-absorbing, and connected to condenser wall 11 through expandable bellows 15, ensures that all forces and torque from the reverse turbine and rotor bearing 6 are transmitted to outlet portion 1 through support plates 3. Thus, the combined turbine unit is capable of making rapid load alterations without jeopardizing the centering between stationary and rotating parts, and stresses on the stationary parts are minimized.

The vertical dividing plane of the turbine unit, defined by flanges 12 between outlet portion 1 and con denser wall 11 and flanges 13 between open shaft 10 and outlet portion 5, is positioned so that turbine rotor shaft 21 can be lifted without disturbing condenser 11, open shaft 10 and inspection chamber 14. As has been noted above, prior art construction required shaft 10 to be strong, heavy, and large enough to be load-bearing and to be mounted within outlet portion 1; the arrangement according to this invention permits lighter construction of shaft 10 and its placement in condenser portion 11, resulting in a considerably shorter, more compact turbine unit.

The alternate embodiment shown in FIGS. 4 and 5 differs from the construction of FIGS. l-3 in that outlet end portion 5 rather than reverse turbine housing 2 is suspended in support plates 3. The framework of struts 4 still symmetrically connects elements 2 and 5.

Since end portion absorbs the side forces on hearing 6, the arrangement of FIGS. 4 and 5 gives more direct support against these side forces, which are transmitted through support plates 3 to outer supports 17 positioned directly below plate 3 and resting against the foundation of the turbine unit.

All other elements in FIGS. 4 and 5 correspond to those previously described for FIGS. l3 and are designated by the same reference characters.

We claim:

1. A main axial turbine combined with a reverse turbine, the rotor of the reverse turbine being operatively mounted on the same shaft as, and adjacent in axial flow direction to, the rotor of the main turbine, with the reverse turbine housing suspended within and coaxial with the outlet portion of the main turbine housing, and comprising:

the reverse turbine housing being formed of a major stator portion and an outlet end portion, said major portion and said outlet end portion circumferentially connected by a symmetrical framework of support struts;

said outlet end portion of the reverse turbine housing carrying therein the bearing which journals the outlet end of the common turbine rotor shaft; and

a symmetrical system of plates, connected to the inside of the outlet portion of the main turbine housing and supportively suspending the reverse turbine housing within said system.

2. Main axial turbine combined with reverse turbine in accordance with claim 1, wherein said symmetrical system of plates supportively suspend said major portion of the reverse turbine housing.

3. Main axial turbine combined with reverse turbine according to claim 1, wherein said symmetrical system of plates supportively suspend said outlet end portion of the reverse turbine housing.

4. Main axial turbine combined with reverse turbine according to claim 1, further comprising an inspection chamber mounted on said outlet end portion of the reverse turbine housing, said inspection chamber being in communication with the outside through an open shaft flexibly attached to the outlet portion of the main turbine' housing by expandable connecting means.

5. Main axial turbine combined with reverse turbine according to claim 1, wherein the inlet tube of the reverse turbine passes through the wall of the outlet portion of the main turbine housing, said inlet tube communicating with and being flexibly attached to said major portion of the reverse turbine housing by a telescopic sealing connection. 

1. A main axial turbine combined with a reverse turbine, the rotor of the reverse turbine being operatively mounted on the same shaft as, and adjacent in axial flow direction to, the rotor of the main turbine, with the reverse turbine housing suspended within and coaxial with the outlet portion of the main turbine housing, and comprising: the reverse turbine housing being formed of A major stator portion and an outlet end portion, said major portion and said outlet end portion circumferentially connected by a symmetrical framework of support struts; said outlet end portion of the reverse turbine housing carrying therein the bearing which journals the outlet end of the common turbine rotor shaft; and a symmetrical system of plates, connected to the inside of the outlet portion of the main turbine housing and supportively suspending the reverse turbine housing within said system.
 2. Main axial turbine combined with reverse turbine in accordance with claim 1, wherein said symmetrical system of plates supportively suspend said major portion of the reverse turbine housing.
 3. Main axial turbine combined with reverse turbine according to claim 1, wherein said symmetrical system of plates supportively suspend said outlet end portion of the reverse turbine housing.
 4. Main axial turbine combined with reverse turbine according to claim 1, further comprising an inspection chamber mounted on said outlet end portion of the reverse turbine housing, said inspection chamber being in communication with the outside through an open shaft flexibly attached to the outlet portion of the main turbine housing by expandable connecting means.
 5. Main axial turbine combined with reverse turbine according to claim 1, wherein the inlet tube of the reverse turbine passes through the wall of the outlet portion of the main turbine housing, said inlet tube communicating with and being flexibly attached to said major portion of the reverse turbine housing by a telescopic sealing connection. 